Surge valve



1952 H. M. PURCELL 2,581,290

' SURGE VALVE Filed July 8 1947 A TTORNEY6' FIG. I

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u B-Y I Patented Jan. 1, 1952 SURGE VALVE Howard M. Purcell,Philadelphia, Pa., assignor to H-P-M Development Corporation,Wilmington, Del., a corporation of Delaware Application July 8, 1947,Serial No. 759,672

2 Claims. (01. 121-38) This invention relates to surge valves for use inhydraulic press actuating circuits and the like, and is particularlyconcerned with a poppet type surge valve.

In hydraulic presses it is customary to have a large main area on a ramand a smaller retracting area. This is due to the fact that the ramgenerally works in only its advancing direction and it is desired tohave a large working area to develop high thrusts and a small retractingarea in order to develop high retracting speeds. The difierentialresulting between the areas requires a surge valve for pre-filling andfor exhausting the main area *when a reversible pump is employed forpowering the press.

During the working stroke of the press ram high pressures are developedon the advancing area thereof and when the press isreversed thispressure must be dissipated at a more or less gradual rate in order toprevent shock, vibrationand noise. This is usually accomplished by anindependent and special valve means connected in the press system.

A preferred type of surge valve to employ is a poppet type valve inwhich the valve member is urged in its opening direction by pressurestanding on the advancing area of the press ram. A valve of this typewill open wide and quickly and permit relatively free flow of fluid toand from the advancing area.

Also, a valve of this type has an advantage over a surge valve whichopens against the pressure on the main area because it may be movedtowards its open position with a much smaller force. a tendency torelieve the pressure on the main area of the press ram so rapidly thatshook, vibration and noise result. 'Ihis is commonly overcome by dampingthe action f.the valve member of the surge valve in a suitable manner sothat it opens at a slow rate of speed and thus gives time for theexcessive pressure on the advancing area to bleed off to a value wherethe aforementioned shock and vibration are greatly reduced or evenentirely eliminated. This treatment of the problem results in slowingdown the-opening of the surge valve to such anextent that in many casesit is undesirable. In presses operating on a very fast cycle the loss ofproduction over a period of time is appreciable.

The present invention is concerned with an improvement in a poppet typesurge valve such that the shock and vibration referred to above areeliminated but in which the surge valve opens in the shortest possibletime thereby creating no However, poppet type surge valves haveunnecessary delay in the operating cycle of the press.

These and other objects and advantages will become more apparent uponreference to the following description taken in connection with theaccompanying drawings in which:

Figure 1 is a diagrammatic view of a press operating circuit adapted foremploying the surge valve of this invention; and

Figure 2 is an enlarged view through the surge valve showing more indetail the construction thereof.

Referring to the drawings, there is a press cylinder In within which isreciprocably mounted a press ram H which forms with the said cylinderthe ram advancing area l3 and the ram retracting area l5.

Connected between the said advancing and retracting areas is a pump I!which is preferably reversible in operation for selectively supplyingthe said areas with pressure fluid.

As will be best seen in Figure 2, the press cylinder H! is extended asat [2 to provide a housing for the surge valve member l4. A closure capi6 is bolted to the upper end of the cylinder by the bolts l8 and has ashouldered bore 20 therethrough intowhich extends the valve memberactuating piston 22 and piston rod 24, the latter icing secured to thevalve member [4.

Retraction pressure is admitted to beneath the piston 22 by a passage 26which is connected by a conduit with the ram retracting area I5, and aspring 28 normally holds the valve member closed until pressure beneaththe piston reaches a predetermined amount.

The reservoir 19 is communicated with the bore in the cylinder Itthrough the transverse passages 30 which open beneath the surge valvewhen the latter raises from its seat. The space above the valve memberis communicated with the main advancing area of the cylinder through aplurality of circumferentially spaced bores 32 passing through the saidvalve member. The larger upper area of the valve member I4 main-.tainsthe surge valve closed until there is a predetermined pressureestablished under the piston 22.

A seat ring 34 is mounted on the bottom of the bore in the upper end ofthe cylinder Ill and is arranged to receive the lower end of the valvemember 14. This lower end of the Valve member I4 includes a cylindricalprojection 36 at the upper edge of which, and beneath the chamfered edge38 of the valve member, there is a groove lll. The groove 40 iscommunicated with the main cylinder cavity by a plurality of drilledholes 42.

In operation, when the press is reversed at the end of a working strokeand the delivery of the pump is initially directed to the retractingarea, the surge valve member commences to move upwardly and the groove40 opens into the bores 5d. This immediately establishes a restrictedpassage to exhaust for the pressure fluid in the advancing area of thecylinder H] with a continued build-up in pressure within the retractingarea of the cylinder, the valve member continues to move upwardly farenough to withdraw the cylindrical skirt 36 from the ring 34 and freecomunication between the reservoir and the main cylinder is established.At this time the retracting speed of the ram increases and substantiallyno time is lost, during the retracting stroke.

In the advancing stroke of the ram, it is necessary to prefill theadvancing area due to the differential in areas between the advancingand retracting sides of the ram. Such prefilling is accomplished bymovement of the valve member M to an unseated position. Such movementtakes place due to the pressure within the retracting area of the ramcaused by the weight of the ram H when the latter occupies an upwardposition within the cylinder I0. Generally, there is a back pressurewithin the retracting area of approximately 50 pounds per square inchwhen the ram is conditioned for advancing movement, and this pressure istransferred to the valve-actuating piston 22 to move the same upwardlyand to unseat the valve member 14, thus providing for full communicationbetween the reservoir and the advancing area of the ram. As the ramcontinues to advance and eventually engages the work, or when resistanceis encountered, the back pressure within the retracting area 15, andconsequently the pressure acting on the piston 22, disappears,permitting the valve member 14 to close under action of the spring 28.Closing movement of the valve member [4 thus disconnects the advancingarea from the reservoir and permits a high pressure build-up within theadvancing area for the continuation of the working stroke of the ram.

By this invention shock at the time of reversal is eliminated in thehydraulic system by giving a controlled bleed 011 of the main cylinderpressure for a short time before the surge valve fully opens. Thiseliminates auxiliary choke and check valves and does not interfere withthe speed of opening the surge valve after the aforementioned bleed offof pressure is accomplished.

It will be understood that this invention is susceptible to modificationin order to adopt it to different usages and conditions and,accordingly, it is desired to comprehend such modifications within thisinvention as may fall within the scope of the appended claims.

I claim:

1. A combination surge and prefill valve for a hydraulic ram having aram-advancing pressure area, a ram-retracting pressure area, and meansto introduce fluid under pressure to either of said areas, comprisingmeans defining a vertically arranged valve chamber communicating at oneend with the ram-advancing area and an exhaust port intersecting thevalve chamber intermediate the ends thereof; a valve member movable insaid chamber between positions openin and closing communication betweenthe ram-advancing area and said exhaust port, said valve member having apassage extending longitudinally therethrough and being formed with aplurality of restricted radially disposed orifices extending from saidpassage to the outer surface of said valve member and arranged adistance inwardly from one end of said valve member, said restrictedorifices being arranged to provide restricted communication between theram-advancing area and said exhaust port upon initial movement of saidvalve member toward its open position and prior to movement of saidvalve member to a position providing for unrestricted communicationbetween the ram-advancing area and said exhaust port; spring meansengaging said valve member and resiliently urging the same to a closedposition; and fluid-pressure-responsive means connected with said valvemember and responsive to the pressure of fluids within theram-retracting area for moving said valve member to an open position inopposition to said spring means.

2. A combination surge and prefill valve for hydraulic rams having aram-advancing pressure area, a ram-retracting pressure area, and meansto introduce fluid under pressure to either of said areas, comprising avalve chamber freely communicating at one end with the ram-advancingarea; an annular valve seat arranged intermediate the ends of saidchamber; exhaust passage means intersecting said chamber intermedi atethe ends thereof and above said valve seat; a valve member movablewithin said chamber into and out of engagement with said valve seat andbetween positions providing for open or closed communication between theram-advancin area and said exhaust passage means, said valve memherbeing formed at one end with a reduced di ameter skirt arranged totelescope within said valve seat and a longitudinal passage extendingthrough said valve member; restricted channel means extending radiallythrough the skirt of said valve member for establishing restrictedcommunication between the ram-advancing area and said exhaust passagemeans upon initial opening movement of said valve member; spring meansengaging said valve member and urging the latter into seating engagementwith said valve seat; and a fluid-pressure-responsive plunger connectedwith said valve member and communicating with the ram-retracting area,and operable, in response to fluid pressure within the ram-retractingarea, for moving said valve mem ber out of engagement with said valveseat.

' HOWARD M. PURCELL.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS

